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Abstract
The effects of a polycyclic aromatic hydrocarbon (PAH) such as naphthalene (NAP)--an
environmental contaminant--and beta-naphthoflavone (BNF)--a model substance (PAH-like
compound)--were investigated in European eel (Anguilla anguilla L.) over 3-, 6-, and
9-day exposure (0.1-2.7 microM). Both xenobiotics revealed to be strong biotransformation
(phase I) inducers. After 3-day exposure, liver ethoxyresorufin O-deethylase (EROD)
activity was significantly increased by all NAP and BNF tested concentrations. At
6 and 9 days, liver EROD activity was significantly induced mainly by the highest
NAP and BNF concentrations. Liver cytochrome P450 content was significantly induced
after 3-day exposure to 0.9 and 2.7 microM BNF and 9-day exposure to 0.1, 0.3 and
0.9 microM NAP. Liver alanine transaminase (ALT) activity was measured as an indicator
of hepatic health condition, revealing a significant decrease after 6-day exposure
to 0.9 microM BNF. Genotoxicity measured as erythrocytic nuclear abnormalities (ENA)
was detected in all BNF treated fish on day 6, whereas on day 9, ENA frequencies returned
to control levels, significantly decreasing at 0.9 microM BNF exposure. Immature erythrocytes
(IE) frequency demonstrated a decreasing tendency along the BNF experiment and concomitantly
with the above ENA response. The present experimental results elect EROD activity
in A. anguilla as a useful short- to medium-term biomarker of exposure to both PAH
and PAH-like compounds. However, some problems can emerge in the presence of high
xenobiotic concentrations. Concerning genotoxicity, it is hypothesized that ENA response
depends on different factors such as the exhaustion of the detoxification process,
the balance erythropoiesis/erythrocytic catabolism and the DNA repairing capacity.